Seriously i get that riot designed them to be these kind of hyper carries, but even without 
, they still do so much dps to well armored targets... Which when you've got 65%+ physical damage resist from armor, yet you still die in less than 3 seconds of a single ADC attacking you, "building more armor" isn't exactly going to do much
Make sure you're building 
and 
, both of which will slow their attack speed by 15% (and they do stack on each other). Randuins also helps against crits, and 
will block 10% right off the bat. Don't just think of the build as "moar armor pleaze" but really consider the added passives that each item grants. In many cases, building these items can be cause to completely omit the standard 
items.
Ok so 65% damage reduction, which is about 2-3 armor items, against an adc with no real armor pen. Lets say you have 2500 hp... The enemy adc has 1200 AD and 2.0 attack speed by the time you have 3 items as tank? :o
"OMG MY ADC DID NO DAMAGE" "But their tanks bought armor"
"My ADC is shit." There's a reason they're called ADCs.
